TEETH 251 



Omura would not expect. Generally speaking, there seems to be no real difference in the number of 

 teeth in male and female sperm whale populations. 



Variation in the numbers of teeth, being independent of age and sex, might be likely to reflect any 

 racial differences which may exist between stocks of sperm whales. Table 10 compares the average 

 tooth numbers calculated from data on whales captured in the Azores and on three other whaling 

 grounds. Omura (1950) specifically mentioned that his counts included unerupted as well as erupted 

 teeth; Matthews' Table VII probably referred to erupted teeth only: therefore the Azores figures 

 have been calculated separately from each kind of count. When this is borne in mind, Table 10 shows 

 a striking agreement between averages, and suggests no racial differences between whales from the 

 North Atlantic and North Pacific or from northern and southern seas. 



Table 10. Average numbers of mandibular teeth in whales from northern and 



southern whaling grounds 



Males Females 



'North 



South 



Locality 

 Azores (Fayal) 1949 and 195 1 



Japan (Omura, 1950) 



South Africa and South 

 Georgia (Matthews, 1938) 



Pelagic Antarctic (Fl. F. 

 Southern Harvester, 1947-8) 



e Counts of erupted teeth only. 



a Counts which also include unerupted teeth apparent as swellings on the gum. 



In some whales rudimentary teeth, usually more or less curved, may be seen protruding from the 

 gum of the upper jaw at or near the edges of the sockets which receive the mandibular tooth cusps when 

 the mouth is shut (Plate I, fig. 7). Boschma (195 1) states that the maxillary teeth can be quite large, 

 but all I have seen have been small compared with the mandibular ones. Table 9 shows that no Azores 

 whale exhibited more than three maxillary teeth a side. These teeth were erupted in five out of twelve 

 males* and in one out of nine females, suggesting that they are erupted more often in males than in 

 females. About 20% of Omura's large sample of North Pacific whales (1950, p. 97), and about 50% 

 of Matthews' southern whales (1938, p. 121), had erupted maxillary teeth. The corresponding figure 

 was 51*5% for ninety-seven males examined aboard Fl. F. Southern Harvester in the Antarctic in 

 1947-8. It would be worth making further counts to see if the maxillary teeth really do erupt more 

 frequently in southern than in northern whales. However, by an incision in the gum I have never 

 failed to expose some maxillary teeth, even in whales where the upper jaw appears superficially tooth- 

 less. No doubt Bennett (1836) was correct in maintaining that small maxillary teeth, whether patent 

 or not, are a constant character in the sperm whale. 



Among the twenty-six whales whose teeth were examined at Horta in 1949, there were three males 

 which had from one to four broken teeth in the front of the lower jaw, and one female with four broken 

 in the middle of the jaw. No carious teeth were observed. 



* Table 9 does not give this information. The table shows that eight whales had no maxillary teeth erupted on the left 

 side and eight had none erupted on the right. But there were only seven whales with no maxillary teeth erupted on either 

 side. 



